It was concluded that the engine stopped when the engine driven fuel pump failed due to the disengagement of the drive shaft splines from the driver gear splines. Because of the suddenness of the failure, the pilot had no warning that a problem existed. The pilot was transiting at 100 feet agl when the power loss occurred, which reduced the number of landing sites available for an autorotation landing. Stretching his glide to cross a creek resulted in a decrease in rotor rpm, which affected the pilot's ability to reduce the helicopter's forward speed and rate of descent prior to touchdown. As a result, the left skid dug into the ground and the helicopter rolled onto its right side. Many factors play a role in the ability of the pilot to carry out an autorotation without damage to the helicopter. In this case cruising at a higher altitude may have eliminated the need to stretch the glide, and allowed the pilot to maintain rotor rpm to control the landing.Analysis It was concluded that the engine stopped when the engine driven fuel pump failed due to the disengagement of the drive shaft splines from the driver gear splines. Because of the suddenness of the failure, the pilot had no warning that a problem existed. The pilot was transiting at 100 feet agl when the power loss occurred, which reduced the number of landing sites available for an autorotation landing. Stretching his glide to cross a creek resulted in a decrease in rotor rpm, which affected the pilot's ability to reduce the helicopter's forward speed and rate of descent prior to touchdown. As a result, the left skid dug into the ground and the helicopter rolled onto its right side. Many factors play a role in the ability of the pilot to carry out an autorotation without damage to the helicopter. In this case cruising at a higher altitude may have eliminated the need to stretch the glide, and allowed the pilot to maintain rotor rpm to control the landing. The engine stopped due to fuel starvation caused by the failure of the engine driven fuel pump. The engine driven fuel pump failed due to excessive wear of the splines of the drive shaft and the driver gear. It could not be determined what caused the excessive wear of the splines. The pilot was flying at an altitude which reduced his choices of landing sites for the autorotation.Findings The engine stopped due to fuel starvation caused by the failure of the engine driven fuel pump. The engine driven fuel pump failed due to excessive wear of the splines of the drive shaft and the driver gear. It could not be determined what caused the excessive wear of the splines. The pilot was flying at an altitude which reduced his choices of landing sites for the autorotation. The engine lost power because the engine driven fuel pump failed. The cause of the pump failure was disengagement of the drive shaft splines from the driver gear splines due to excessive wear.Causes and Contributing Factors The engine lost power because the engine driven fuel pump failed. The cause of the pump failure was disengagement of the drive shaft splines from the driver gear splines due to excessive wear. The Chandler Evans Control Systems Division is continuing to investigate a number of possible external causes of the premature and excessive wear of the splines, such as misalignment in the pump or engine gearbox, fuel contamination, harmonic vibrations, flow rate through the splines, and fuel lubricating qualities. On 30 July 1997, Chandler Evans Control Systems Division initiated the collection of most of the 567 model MFP263 pumps that had been delivered at the time of this occurrence, for tear-down examination of the drive splines. It is reported that several pumps were found to have abnormal wear on the splines. Allison Engine Company issued a Commercial Engine Bulletin on 21 August 1997, requiring removal and inspection of the affected fuel pumps for drive shaft backlash, which would be an indication of wear. Initial inspection is to be accomplished within 25 operating hours from receipt of the bulletin, with recurring inspections every 100 hours thereafter until further notice.Safety Action The Chandler Evans Control Systems Division is continuing to investigate a number of possible external causes of the premature and excessive wear of the splines, such as misalignment in the pump or engine gearbox, fuel contamination, harmonic vibrations, flow rate through the splines, and fuel lubricating qualities. On 30 July 1997, Chandler Evans Control Systems Division initiated the collection of most of the 567 model MFP263 pumps that had been delivered at the time of this occurrence, for tear-down examination of the drive splines. It is reported that several pumps were found to have abnormal wear on the splines. Allison Engine Company issued a Commercial Engine Bulletin on 21 August 1997, requiring removal and inspection of the affected fuel pumps for drive shaft backlash, which would be an indication of wear. Initial inspection is to be accomplished within 25 operating hours from receipt of the bulletin, with recurring inspections every 100 hours thereafter until further notice.